The present invention relates to an automatic reproducing apparatus and particular to the frame assembly used in such apparatus. In particular, the present invention relates to a frame assembly including a lower frame member having a plurality of mounting elements attached thereto which are arranged in parallel fashion from the front of the machine to the back of the machine to enable the mounting of individual reproducing apparatus components thereto to provide the assembly of reproducing machines having one of a plurality of process widths.
Historically in the manufacture of automatic reproducing machines, the construction initially was based on a main frame comprising one or more large die castings of aluminum or the like to which operational subassemblies such as developer housing, cleaner housing or copy sheet transport would be mounted. Often times the subassemblies themselves were built on a small die cast frame members to which each of individual subassembly parts had to be fixed. Some machines, in large part, consisted of massive frames and subframe structures to which the individual operational elements were directly mounted or mounted through brackets. Typical of commercial products of this nature were the Xerox 914 and 3600 model copiers. The Xerox 3600 model is exemplified in U.S. Pat. No. 3,301,126 to Osborne et al.
The next step in the development of the frame structure was the use of sheet metal as the principle frame structure. Although some die castings were still used for mounting subassemblies, a rapid switch to the use of sheet metal and steel bracketing replaced the high level use of metal die castings. However the individual operational parts of the machine continued to be assembled first as a subassembly which was mounted to the main frame. Exemplary of this type of copier construction is the Xerox 4000 copier.
A later development in automatic reproducing machine construction was the use of a unitized type of construction which uses a sheet metal frame with as many of the individual operational elements being mounted directly to it. In this type of construction, the use of subassemblies is to a very large degree replaced by mounting the individual elements directly to the sheet metal frame. This type of construction is exemplified by that found in the Xerox 3300 copier. A variant of this type of construction uses straight pieces of sheet metal with punched and machined holes for mounting supporting brackets and machine elements.
In all these techniques, a very large number of suitable brackets, holders or subassembly frames are required to hold or mount every single piece of the entire operational structure of the machine onto the frame assembly. The number of parts including mounting blocks, brackets and fasteners is very large. In addition, it is necessary to drill or tap several suitable mounting holes in the frame and subframe structures. Further and perhaps most important from an operational sense, every mounted element or assembly must be adjusted for operational tolerances relative to its frame structure as well as relative to the other operational elements or assemblies with which it interacts. For example, the developer assembly, charging corotron assembly and cleaning assembly must all be aligned and adjusted for operational tolerances with the photoconductor drum. It also frequently happens that these adjustments become loose with time and use and must be continuously aligned for maximum operational efficiency and copying quality. In addition the assembly costs to put all these parts together and adjust them increases to a very high degree as the number of parts and complexity of adjustment increases. Simply said, it cost more to install every single screw in a machine.